Linux kernel: CMA & Device Tree

Question

I've tried to use the CMA (Contiguous Memory Allocator) configured with DT. But how can I access the allocated memory region form the module?

This is the DT part:

reserved-memory {
    #address-cells = <1>;
    #size-cells = <1>;
    ranges;

    dsp_reserved: dsp@83400000 {
        reg = <0x83400000 0x400000>;
        no-map;
    };
};

c64_dsp {
    compatible = "c64-dsp";
    interrupt-parent = <&intc>;
    interrupts = <26>;
    memory-region = <&dsp_reserved>;
};

How can I get the reserved memory region "dsp_reserved" in my own driver? Is this region already requested by "dma_alloc_coherent"? Is there a function similar to "platform_get_irq"?

Thanks for help, Sven

Answer 1

I've found a solution (called in probe() function):

memory = of_parse_phandle(dev->of_node, "memory-region", 0);
if (!memory) {
    return -ENODEV;
}

addr = of_translate_address(memory,
             of_get_address(memory, 0, &memory_size, NULL));

virt_addr = phys_to_virt(addr);